A gate-tunable graphene Josephson parametric amplifier

TL;DR

This paper demonstrates a graphene-based Josephson parametric amplifier with wide frequency tunability, high gain, and near-quantum-limited noise performance, advancing electrically tunable quantum circuit technology.

Contribution

It introduces a novel graphene Josephson junction amplifier with broad tunability and high performance, filling a gap in semiconductor weak link-based quantum amplifiers.

Findings

Gain exceeds 20 dB

Working frequency is widely tunable with gate voltage

Noise performance approaches the quantum limit

Abstract

With a large portfolio of elemental quantum components, superconducting quantum circuits have contributed to dramatic advances in microwave quantum optics. Of these elements, quantum-limited parametric amplifiers have proven to be essential for low noise readout of quantum systems whose energy range is intrinsically low (tens of $\mu$eV ). They are also used to generate non classical states of light that can be a resource for quantum enhanced detection. Superconducting parametric amplifiers, like quantum bits, typically utilize a Josephson junction as a source of magnetically tunable and dissipation-free nonlinearity. In recent years, efforts have been made to introduce semiconductor weak links as electrically tunable nonlinear elements, with demonstrations of microwave resonators and quantum bits using semiconductor nanowires, a two dimensional electron gas, carbon nanotubes and graphene. However, given the challenge of balancing nonlinearity, dissipation, participation, and energy scale, parametric amplifiers have not yet been implemented with a semiconductor weak link. Here we demonstrate a parametric amplifier leveraging a graphene Josephson junction and show that its working frequency is widely tunable with a gate voltage. We report gain exceeding 20 dB and noise performance close to the standard quantum limit. Our results complete the toolset for electrically tunable superconducting quantum circuits and offer new opportunities for the development of quantum technologies such as quantum computing, quantum sensing and fundamental science.